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Digitized by the Internet Archive 
in 2011 with funding from 
The Library of Congress 



http://www.archive.org/details/cruiseofschoolshOOnewy 



U- . jv .,. 



Department of ]JuOftc dOaritics aiif) (Coirection 



CEUISE 



SCHOOL-SHIP "MERCURY" 



TROPICAL ATLANTIC OCEAN. 



J 1870-1871. ^L,^^^ 



^ ^ ^ 



KEW YOEK: 

THE KEW YORK PRINTING- COMPANY, 

Nos. 81, 83, AND 85 Centre Street. 

1871. 






\ 



REPORT 



Department of Public Chaeities and Correction, ) 

Corner of Third avenue and Eleventh street^ V 

Kew YorKj September I25 1871. ) 

Hon. A. Oakey Hall, Mayor : 

Sir— The Commissioners of Public Charities and Correction respect- 
fully submit a report of the practice-cruiso of the school-ship Mercury, 
from her anchorage ground at Hart's Island to Sierra Leone, and from 
thence via St. Thomas to this port, during the winter of 1870-71. 

But, before narrating the history of the cruise, it is proper to state 
more specifically than in the annual report the reasons which induced 
the Commissioners to establish a nautical school, and to describe the 
character of the boys who are assigned to it. With the increase of the 
population of the city there had been a greatly increased number of 
boys committed to the care of the Commissioners by the magistrates, 
for slight misdemeanors and vagrancy. Others, and in large numbers, 
had been committed by their parents as incorrigible, or because of evil 
associates, who were leading them to ruin. These boys were at first 
sent to the Industrial Schools on Hart's Island, but the number in- 
creased so rapidly that the Commissioners w^ere embarrassed as to the 
disposition which should be made of them. 

They could not without a long probationship be recommended as ap- 
prentices, because of tlieir wayward and reckless character, nor could 
they be discharged without the probability that they would again 
become vagrants, or fall into their former wicked associations. Under 
these circumstances it was deemed expedient to establish a nautical 
school, as well for the purpose of relieving the department of a con- 
stantly increasing number of unruly boys, as of providing for them a 
sure and honest means of livelihood suited to their adventurous spirit. 



Wlieii the school was establisliecl it was contemplated from considera- 
tions of economy to teach them the rudiments of seamanship while the 
ship was at anchor in the harbor, and by occasional trips of short 
duration at sea, during the summer months ; and this method was fur- 
ther commended by the consideration that the boys w^ould be under 
the direct and constant supervision of the Commissioners. 

But the experience of a few months demonstrated that the oiily effec- 
tual mode of instruction is the continuous handling of a sliip at sea, 
and that the manifold duties of a thorough seaman can oidy be learned 
by actual service. 

The cruise, of which the following papers constitute the report, was 
made in pursuance of these convictions and for the purpose of qualify- 
ing the boys for immediate entrance on their return into the service of 
the navy or mercantile marine. In this respect the result of the cruise 
was highly satisfactory, for of the crew of two hundred and fifty-eight 
boys over one hundred were, in the opinion of the captain, capable on 
the return of the ship of discharging the duties of ordinary sea- 
men. 

It is proposed to apply to Congress at its next session for authority to 
be vested in the Secretary of the Navy to discriminate in enlistments 
in favor of boys who have been educated in school-ships. 

The exploration of the ocean has become an object of deep interest 
to governments as well as to men of science. The United States Coast 
Survey, under the wise direction of Professor Baclie, and now of Pro- 
fessor Pierce, has for many years been diligently engaged in adding to 
the limited information possessed of deep-sea soundings, temperatures, 
and currents, and more recently the British Government, under the su- 
pervision of Dr. Carpenter, has solved several problems of scientific 
importance, added largely to the stock of general knowledge, and made 
discoveries which will be of practical benefit to commerce and naviga- 
tion. 

With the hope that the cruise of the Mercury might be made to con- 
tribute something of value to science. Captain Giraud w^as directed to 
obtain a series of soundings on the line of or near the Equator, from the 



coast of Africa to the mouth of the Amazon, to observe the set of the 
surface currents, and the temperature of the water at various depths. 
The following is a copy of his letter of instructions : 



Department of Public Charities and Correction, ) 
New York, December 13, 1870. f 

Sir — You will proceed to sea, in command of the Mercury, on the 
16th instant, by way of Montauk Point, and cruise between the latitudes 
10° north and 5° south of the equator, and of longitude from 5° east to 
45° west of Greenwich, until the 10th of March, when you will return 
to your anchorage at Hart's Island, unless on your approach to the coast 
you shall deem it prudent, from stress of weather, to enter at Sandy 
Hook. 

You will keep at sea as much as possible, going into port only to 
obtain water and provisions or for repairs. As often as may be prac- 
ticable, you will forward to this office detailed reports of the health of 
the officers and crew, and the progress made By the boys in seamanship 
and in their studies at school. 

The routine duties of the ship, as laid down in the rules for the edu- 
cation of the boys in seamanship, will be strictly adhered to. 

You will, as often as may be practicable, take soundings of the bed 
of the Atlantic, on or near the line of the Equator, from the coast of 
Africa to the mouth of the Amazon. 

You will also frequently observe and record the temperature of the 
ocean at the surface and at twenty, fifty, one hundred, and two hun- 
dred fathoms, and obtain specimens of water at those depths, which 
you will cause to be evaporated on board, and the solid matter ana- 
lyzed, or you will bring the specimens home in bottles provided for the 
purpose. 

You will also obtain sea-plants from as great depths as may be prac- 
ticable, together with animalculse and other minute forms of animal 
life, which you will preserve or cause accurate drawings thereof to be 



made, for wliicli purpose you will be furnished with a microscope of 
large powers. 

An accurate knowledge of the set and velocity of currents is of 
great importance to commerce. You will be pleased to note and care- 
fully determine the direction of all currents with which you may 
fall in. 

A favorable opportunity will be afforded to note with approximate 
accuracy their rate and direction when you are engaged in taking your 
deep-sea soundings from an open boat. 

It is desirable that the misplaced reliance of many navigators on 
dead-reckoning may be demonstrated, and to this end you will fre- 
quently, when you have determined your position by astronomical 
observation, throw your registering log and let it remain in the water 
for twenty-four or forty-eight hours, or until you have taken another 
observation, when you will compare the progress you have made by 
dead reckoning with your actual progress, as determined by observation. 

While the chief object of the cruise of the Mercury will be to per- 
fect the boys under your command in seamanship, the Commissioners 
indulge the hope that, by the careful observation of yourself and officers, 
the interests of commerce may be promoted, and the cause of science 
advanced. 

Yery respectfully, 

ISAAC BELL, 

President, 
To Caj^tain Piekee Giraud, 

Coininanding ScJiool-sJiip Mercitry. 

The ship sailed from Hart's Island on the 20th December, 1870, and, 
after stopping at Madeira and the Canary Islands, arrived at Sierra 
Leone on the 14th of February. 

On the 21st of February she left Sierra Leone, and on the 22d Cap- 
tain Giraud connnenced his deep-sea soundings, which he continued in 
nearly a straight line to the Island of Barbadoes, a distance of about 



2,800 miles. His soundings range from 500 fathoms to 3,100 fathoms, 
or 3J- miles, from which depths he brought up in most instances speci- 
mens of bottom. The current observations will be of value in the 
navigation of the South Atlantic, and the ascertained temperatures of 
the water at from 200 to 500 fatlioms are confirmatory of the theory that 
a cold current from the Poles underlies the surface-waters of the tropi- 
cal seas. 

The daily meteorological observations, the direction and velocity of 
currents, and the temperatures of the oc^an at various depths, are set 
forth in his report, which is herewith annexed. These papers, together 
with the specimens obtained from the bed of the ocean and of sea- 
w^ater, were placed in the hands of Professor Henry Draper of the Kew 
York University for examination. 

Professor Draper's report, which is herewith submitted, contains 
precise tabulated statements of the meteorological observations of the 
voyage, of the direction and velocities of the currents, and of the 
temperatures at the several depths obtained, together with an analysis 
of the specimens of water from various depths. The report also con- 
tains a diagram of the bed of the Atlantic, i'rom Sierra Leone to 
Barbadoes, as established by the soundings, and is replete with interest- 
ing disquisitions on all the questions of deep-sea explorations. The 
specimens of animal life which were obtained from the bottom were 
forwarded for examination by Professor Draper to Dr. Carpenter. He 
reports that they are the ordinary forms of deep-sea foraminifera. 
With the specimens Professor Draper also sent a table of the tempera- 
tures, and in respect to them Dr. Carpenter remarks, " that they are of 
great interest, and especially those at one hundred and two hundred 
fathoms. They show,'' he continues, " how thin is the surface stratum 
affected by the gulf -stream, or by direct solar radiation. The sudden 
drop," he remarks, *^ in the temperature at two hundred fathoms, between 
17° 46' west longitude, and 19° 36' west longitude, and the continuation 
of this reduction with the increased westing as far as 50° 38' is a very 
curious phenomenon, and I cannot help connecting it with some great 
oceanic movement, especially as at 68° 47' west longitude, and at 83° 
the higher temperatures reappear. I trust that hereafter much atten- 
tion will be given to this point." 



Tlio conclusion at which Professor Draper has arrived, from a care- 
ful examination of the results obtained, is that there exists, all over the 
bottom of the Atlantic and Caribbean Sea, a stratum of cold water, 
and that the ci'uise of the Mercury must be considered as offering con- 
firmatory proof of the correctness of Dr. Carpenter's theory, drawn 
from the cruises of the Englisli exploring vessels, that there is a general 
movement of the lower w^aters of the Atlantic towards the Equator, 
and a corresponding flow of the surface-waters towards the Poles. 

The object of the cruise was, as has been stated, to perfect the boys 
in seamanship. The scientific explorations were incidental and subsi- 
diary, but enough has been accomplished to encourage the hope that the 
practice voyages of the Mercury may be made to contribute to the 
stock of knowledge, and help to explain the mysteries of the Great 
Deep. 

The experiment of the school-ship, as a Reformatory, has thus far 
been satisfactory. There is reason to believe that it is the most effec- 
tive mode to reclaim erring boys, whose errors, caused by the love of 
adventure, by evil associations, or ungovernable tempers, are fast hn- 
pelling them to ruin. Brought under the inflexible discipline of a 
ship in actual service, they are taught in a few months the duties of a 
profession, wdiich directs and gratifies their love of adventure, and pro- 
vides for them the means of an honest and useful livelihood. 

Eespectf ully submitted. 

Isaac Bell, 1 ^> . . 

Owen W. Brennan, (^o^J^i^^^^ners 

Jas. B. Nicholson,' V ,f ^^^^^^ , 
Alex. Feear, | <^f^r^t^e8(lnd 

James BowEN, J (Correction. 



int/i the res(>ccts of 

Professor HENRY DRAPER, M. D. 



University of the City of Nnv York. 



REPORT 



oinmififiioner^ of ;)ubl^ lluiritij^ am! H^orrfctiou 



CITY OF NEW YORK, 

ON THE CHEMICAL AND PHYSICAL FACTS COLLECTED FROM THE 

DEEP SEA RESEARCHES 

MADE DURING THE VOYAGE OF THE 

NAUTICAL SCHOOL-SHIP "MERCURY," 

UNDERTAKEN BY THEIR ORDER IN THE 

TROPICAL ATLANTIC AND CARIBBEAN SEA, 

1870-71. 

By henry DEAPEE, M.D., 

Professor of Analytical Chemistry and Physiology in the University of New York. 



11 



REPORT. 



GontenU — Introduction — Outline op voyage — Its three stages— General air tem- 
perature—Barometric TABLE — Pressure increases on nearing America — Tables 
OF sea currents— Collection of samples op water, and necessary precau- 
tions—Effects of pressure on gaseous and saline ingredients- Determination 
OP specific gravity of samples collected, with table — Thermometric observa- 
tions, with description of registering thermometer — Tables op air tempera- 
tures, AND OP water at VARIOUS DEPTHS — DISCUSSION OF SOUNDINGS — CrOSS- 

section of Atlantic— Suggestions of effect of Amazon and Orinoco — Tempera- 
ture AND specific GRAVITY OP WATER INCREASE TOWARD WeST — PrOOF THAT A 
STRATUM OF COLD WATER EXISTS AT THE BOTTOM OP THE TROPICAL ATLANTIC— EXAM- 
INATION OF DISSOLVED GASES, OF ORGANIC MATERIAL— SPECTRUM ANALYSIS OF SOLID 

RESIDUES — Organic remains. 

The Commissioners of Public Charities and Correction, having sub- 
mitted to me for examination certain documents and specimens con- 
nected with the voyage of the nautical school-ship Mercury, I have 
the honor to make thereupon the following report ; 

Much attention has recently been given to deep-sea researches, in 
consequence of the investigations made by the United States Govern- 
ment on its coast, and by Dr. Carpenter, Mr. Gwyn Jeffreys, and Pro- 
fessor Wyville Thomson, in the North Atlantic and the Mediterranean 
Sea. IN^ot only have many of the facts so ascertained been corroborated 
by this voyage of the Mercury, but the Commissioners, by authori- 
zing it, have also added much that is new and interesting to our 
knowledge of the physical condition of the deep sea. 

The voyage of the , Mercury may be divided into three stages : 
1st, from K'ew York, by way of the Madeira and Canary Islands, to 
Sierra Leone ; 2d, from Sierra Leone, tlu'ough the tropical Atlantic, to 
Barbadoes ; 3d, from Barbadoes, through the Caribbean Sea, to the 
north of Cuba, and thence, along the coast of the United States, back 
to New York. 

The chief scientific interest of this voyage is connected with its 
second and part of its third stage. 



12 

The sliip left Kew York on December 20, 1870. Slie reached Funchal 
(Miideira Islands) on January 17, 1871 ; Las Palmas, in the Canaries, 
on January 2-i, and Sierra Leone on February 14. On the 21st of that 
montli she sailed for Barbadoes, and reached that island on the morn- 
ing of March 17. She sailed from Barbadoes on Marcli 2'4j and ar- 
rived in New York on April 21. 

It is necessary to give these particulars, with a view of indicating 
that tlie voyage was made in the winter season of the year, the season 
of the lowest air temperatures. The mean temperature of the air at 8 
P.M., while at Funchal, was 70|-°, the maximum being 70° aud the min- 
imum 6S°. "While at Las Palmas it was 63°, the maximum being ()Q° 
and the minimum 57°. While at Sierra Leone it was 83°, the maximum 
being 85°, the minimum 79°. In the passage across the Atlantic, from 
Sierra Leone to Barbadoes, the mean temperature was 7S|-° ; the max- 
ima were on leaving the African and on approaching the American 
coast. For nearly a fortnight, during the mid-passage, the variations 
were included between 76° and 79°. 

In this report the degrees of temperature are according to Fahren- 
heit's scale. Though the thermometer was observed regularly, three 
times each day, at midnight, at noon, and at 8 p.m., I have adopted the 
latter only, since it is recognized by meteorologists that the tempera- 
ture at 8 P.M. very closely approaches the mean for the entire day. 

As regards the barometer, the following table v^ill show its height, 
as determined by three observations each day during the passage from 
Sierra Leone to Barbadoes : 



13 



Table I. 

Barometric Ohservations from Sierra Leone to Bai'ladoes. 



DATE. 


MIDNIGHT. 


NOON. 


8 P.M. 


Feb 21 


29.64 
29.70 
29.76 
29.70 
29.68 
29.74 
29.76 
29.74 
29.68 
29.72 
29.72 
29.72 
29.72 
29.80 
29.78 
29.78 
29.79 
29.76 
29.77 
29.74 
29.78 
29.82 
29.80 
29.78 


29.66 
29.68 
29.70 
29.68 
29.68 
29.74 
29.76 
29.68 
29.66 
29.68 
29.70 
29.74 
29.73 
29.78 
29.78 
29.76 
29.79 
29.76 
29.73 
29.76 
29.76 
29.81 
29.80 
29.78 


29 60 


Feb 22 


29 70 


Feb. 23 


29 74 


Feb 24 


29 66 


Feb. 25 


29 70 


Feb. 26 


20 74 


Feb. 27 


29 76 


Feb. 28 


29 64 


Marcli 1 . 


29 66 


March 2 

Marcli 3 


29.68 
29 70 


March 4 


29 72 




29.74 

29 78 


March 6 


March 7 


29 78 


March 8 


29 76 


March 9 . . .... 


29 78 


March 10 


29 76 


March 11 


29 73 


March 12 


29 76 


March 13 


29 76 


March 14 


29 82 


March 15 


29 74 


March IG 


29 80 






Mean of all the observations '. . . 


29.745 


29.733 


29.730 



From this it will be seen how small the barometric variations were. 
Examining, for instance, those of 8 p.m., the minimum was only J/-Q-inch 
below, and the maximum y|-Q-inch above tlie mean. It may also be 
remarked that, in a general manner, the pressure of tlie air increased 
on Hearing the American coast. 

On leaving the African coast the atmosphere was liazj, as is usual 
in that region. On March 5 the north-east trade winds wxre struck, 
and they accompanied the ship to Barbadoes. Previously to reaching 
them her mean daily progress had been only 57 miles ; after that time 
it was 187 miles. 

The ocean currents, as reported on the days when other important 
observations were made, are shown by the following table : 



14 

Table II. 

Direction and Velocity of Currents hetioeen Sierra Leone and 

Barhadoes. 



Date. 


Direction, 


Velocity. 


1 

Date. 


Direction. 


Velocity. 


Feb. 23 


S.W. 


y knot. 


1 

March 4 


S. 


K knot. 


" 25 


S. S.W. 


X knot. 


'' 10 


S.W. 


K knot. 


'* 26 


S. by W. 


}4 knot. 


" 11 


S.W. by W. 


% knot. 


" 27 


S 


}4 knot. 


" 13 


W. S.W. 


% knot. 


" 28 


S. by W. 


}4 knot. 


•' 14 


W. S.W. 


i| knot. 


March 3 


S. S.W. 


% knot. 


'' 15 


W. 


y^ knot. 



Table III. 

Direction and Velocity of Currents in the West India Seas. 



Date. 


Direction. 


Velocity. 


Date. 


Direction. 


Velocity. 


April 4 


W. 
W. 

W. by N. 
W. by ]^. 


y knot. 
}4 knot. 
y knot. 
3>| knot. 


April 8 


W. N.W. 

W. 

S.W. 

N. N. W. 


y knot. 
}i knot. 


" 5..".".".'"'.'.'. 


'' 9 


"6 


" 11 


% knot. 




" 13 


Jl" knot. 









During the second stage of her voyage the ship's track was over a par- 
allel included substantially between the eleventh and thirteenth degrees 
of north latitude. She obtained soundings at various depths, from 290 to 
3,100 fathoms, and on eleven occasions specimens from the bottom. In 
the third stage of her voyage, while in the West Indian seas, three 
other bottom-specimens were secured. The apparatus used was Brooks' 
detaching apparatus, with two thirty-two pound shot. The sounding- 
line was cotton cord, one-seventh of an inch in diameter. All the 
soundings were made from a boat. On March 6, the maximum depth 
of 3,100 fathoms in the Atlantic was reached, but on reeling in, the 
line unfortunately parted, and 2,200 fathoms were lost. This is one 
of the deepest accurate soundings ever made. 

Samples of water from the surface, and also from deptlis varying 
from two hundred to five hundred fathoms, as shown in Table lY., 



15 

were procured. The temperature of the sea, both at the surface and 
at those depths, was ascertained. The samples of water were collected 
in the usual apparatus, a metal cylinder, presently to be more particu- 
larly described, having at its bottom and top valves opening upwards. 
By this contrivance as water obtained from a great depth is drawn 
toward the surface, it and its included gases have liberty to expand, the 
excess escaping through the upper valve. If such provision were not 
made, the cylinder, no matter how strong it might be, would unavoida- 
bly be burst open. It should be borne in mind that the compressil)ility 
of water is about ^^^^q for each atmosphere of pressure it sustains, and 
at depths such as were here reached the pressure was about 1,250 
, pounds per square inch, or more than eighty atmospheres. 

There are certain precautions which must be attended to in the use 
of this collecting cylinder. These more particularly refer to securing 
the perfect action of its valves. It is intended that these valves should 
remain open during the entire period of the descent of the cylinder in 
the sea, and remain closed during its ascent, except in so far as the 
upper one may be opened by the interior pressure to allow the excess 
of included water and its dissolved gases to escape. Obviously, how- 
ever, these conditions may be interfered with by a variety of accidental 
causes, such as the adhesion of the valves by verdigris or other im- 
purity, or by the cylinder assuming an inclined instead of a vertical 
position. 

The constitution of the water as it exists at great depths is not cor- 
rectly represented by the samples thus obtained. A considerable por- 
tion of the gases dissolved therein may escape, as j iist stated, under the 
relief of pressure as the cylinder is drawn toward the surface, and hence 
examinations of such samples, as regards their gaseous ingredients, are 
liable to be deceptive. The low temperature and great pressure of 
these deep strata, moreover, increase the solvent power of the water 
over gases, and this power is diminished as the cylinder is brought into 
the warmer strata above, and into the open air. Even the saline ingre- 
dients will suffer disturbance when they are held in solution by gases 
that will thus escape. For instance, this is the case with carbonate of 
lime. 'No method has hitherto been practised which furnishes a means 



16 

of obtaining samples of sea-water from great depths with their true 
constitution undistui-bed, though obviously an apparatus might be de- 
vised which would accomplish that purpose. 

As thus procured the specimens of water were preserved in well- 
corked glass bottles with sealing-wax on the cork, until submitted to 
me for examination. These samples are fifty in number, divisible into 
two groups, surface and deep ones, from each locality. In quantity 
they vary from four to sixteen ounces. 

I have determined the specific gravities of these specimens and most 
of them are inserted in Table lY. To insure correct results sevei-al 
precautions must be taken. The difference of density between water 
collected at the surface and that from great depths is so small that a 
slight variation in temperature is sufticient to mask it completely. 
Hence it is only in laboratories, Avhei-e means can be used to provide 
against temperature variations and where balances of precision can be 
employed, that accurate results can be obtained. It will, therefore, be 
imderstood that in the experiments upon which the following table has 
been constructed such precautions have been carefully attended to. It 
may be remarked that on board ship, where, on account of the motion, 
balances cannot be applied, the hydrometer maist be resorted to, but 
any conclusions drawn from its indications should be accepted with 
much reserve. It is difiicult to read its scale wutli exactness, and it is 
almost impossible under such circumstances to secure the proper tem- 
perature conditions. In some of the more interesting instances the 
variation of a single degree in the temperature would lead to a conclusion 
in direct opposition to the true one. 



17 



Table IY. 
Kcijic Gravity of Samples of Sea-icater at 75' 



DATE. 


LATITUDE. 


LONGITUDE. 


DEPTH. 


SPECIFIC 
GKAVITY. 


Feb. 25 


9° 14' 

9° 14' 
10° 04' 
10° 04' 
10° 42' 
10° 42' 
11° 35' 
11° 35' 
11° 39' 
11° 39' 
11° 35' 
11° 35' 
11° 06' 
11° 06' 
12° 38' 
12° 38' 
13° 02' 
13° 02' 
13° 06' 
13° 06' 
13° 08' 
13° 08' 
12° 55' 
12° 55' 
17° 13' 
17° 13' 
17° 08' 
17° 08' 
17° 09' 
17° 09' 
17° 27' 
17° 27' 
17° 27' 
18° 11' 
18° 11' 
19° 12' 
19° 12' 
20° 17' 
20° 17' 
20° 48' 
20° 48' 
23° 19' 
, 23° 19' 
23° 19' 


17° 09' 

17° 09' 
17° 33' 
17° 33' 
17° 46' 
17° 46' 
18° 20' 
18° 20' 
18° 33' 
18° 33' 
19° 35' 
19° 35' 
21° 55' 
21° 55' 
42° 31' 
42° 31' 
44° 51' 
44° 51' 
50° 38' 
50° 38' 
53° 48' 
53° 48' 
56° 46' 
56° 46' 
67° 29' 
67° 29' 
68° 48' 
68° 48' 
71° 47' 
71° 47' 
74° 33' 
74° 33' 
74° 33' 
76° 00' 
76° 00' 
77° 54' 
77° 54' 
80° 35' 
80° 35' 
83° 02' 
83° 02' 
84° 17' 
84° 17' 
84° 17' 


Surface 


1026 72 


Feb. 25 


200 fathoms 

Surface 


1026 68 


Feb 26 


1026 42 


Feb 26 


200 fathoms 

Surface 


1026 50 


Feb. 27 


1026 72 


Feb. 27 


200 fathoms 

Surface 


1026 66 


March 1 


1026 53 


March 1 


200 fathoms 

Surface 


1026 53 


March 2 


1026 80 


March 2 


200 fathoms 

Surface ... 


1026 80 


March 3 


1026 76 


March 3 


200 fathoms 

Surface 


1027 00 


March 4 


1026 92 


March 4 


200 fathoms 

Surface 


1026 77 


March 10 


1027 28 


March 10 


200 fathoms 

Surface 


1027 32 


March 11 


1027 10 


March 11 


200 fathoms. . . . 
Surface 


1027 28 


March 12 


1026 58 


March 12 


200 fathoms 

Surface , 


1026 81 


March 13 


1026 72 


March 13 


420 fathoms 


1026 88 


March 15 


1026 53 


March 15 


100 fathoms 

S\irface 


1027 03 


April 4 


1026 83 


April 4 


400 fathoms 

Surface 


1026 87 


April 5 


1026 78 


April 5 


200 fathoms 

Surface 


1026 83 


April 6 


1026 87 


April 6 


(9) 


1026 79 


April 7 


Surface . . . 


1026 88 


April 7 


300 fathoms 

400 fathoms 

Surface 


1027 03 


April 7 

April 8 


1027.16 

1026 88 


April 8 


200 fathoms 

Surface 


1026 83 


April 9 


1027 04 


April 9 


200 fathoms 

Surface 


1026 96 


April 10 


1027 56 


AprH 10 


100 fathoms 

Surface 


1027 48 


April 11 


1027 08 


April 11 


200 fathoms 

Surface 


1027 04 


AprU 13 


1027 16 


AprU 13 


100 fathoms 

200 fathoms 


1027 20 


April 13 


1027 16 








Tlie temperatures under the sea-surface were obtained by a self- 
registering thermometer of the form known as Six's construction. It 
had no provision to protect it from variations of pressure. Compensa- 

2 



18 



tion for tliese variations must be determined in tlie case of each indi- 
vidual instrument, for the amount of this error will vary with the 
varying thickness of the glass, its form, and its power of resisting com- 
pression. In the experiments made by Dr. Miller on self-registering 
thermometers for deep sea sounding, published in the report of the 
Meteorological Committee of the lloyal Society for 18G9, it is show^n 
that certain nnprotected thermometers submitted to a pressure of two 
and one half tons per square inch in a hydraulic press, though made 
wdth bulbs of nnusual thickness, would indicate 
temperatures from 6j\° to 8j\° too higli, and in 
other experiments when the pressure was raised to 
three tons on tlie inch the error was ll-J-°. In these 
instances, however, a part of the rise, perhaps as 
mnch as 1-^-°, was due to the heat disengaged from 
the water itself in the act of compression. In 
most of the sul)joined observations, the depth not 
exceeding 200 fathoms, the pi-essure upon the ther- 
mometer was one quai'ter of a ton per square inch. 
In the apparatus used on board the Mercury, the 
thermometer was inclosed in the water-collecting 
cylinder. It was, as in Six's form, alcoholic, the 
reservoir consisting of a tube about five inches long 
and one-third of an inch in diameter, made of pretty 
substantial glass, and, though the influence of 
pressure upon it has not yet been determined ex- 
perimentally, tliere is reason to suppose that at the 
depths in. question the en'or would not exceed one 
or two degrees. No index error was found on 
comparing this instrument with a standard Kew. 




The wnter-collecting cylinder consisted of a copper 
tube thirteen inches long and one and three quar- 
ters in diameter, weiglited witli a hollow cone of 
lead at its lower extremity. The valves above and 
below were one inch in diameter. In w^hat may be 
called the front of the cylinder there were inserted 
SECTION OF WATER-COL- strips of platc glass, through which the indications 



LECTING CYLINDER AND 
THERMOMETER. 



of the thermometer might be read without removing 



19 

it from the cylinder. The glass was protected from injnry bj brass 
rods. 

In the above figure cm is the copper cylinder, he the two valves, 
dd the handle for connection to the sounding line, e the Six's ther- 
mometer, ff^Q weight at the bottom. 



Table Y. 



Air Temperatures between Sierra Leone and the Flmida Capes 





Temperature of 


Air at 




Temperature of 


Air at 


Date. 








Date. 










IMidnight. 


Noon. 


8 p.m. 


Midnig-ht. 


Noon. 


8 p.m. 


Feb. 21.... 


79° 


84° 


81° 


Mar. 14. . . . 


78 


81° 


81° 


" 22.... 


79° 


84° 


83° 


" 15.... 


74° 


79° 


77° 


" 23.... 


80° 


83° 


79° 


" 16.... 


79° 


85° 


85° 


" 24.... 


78° 


81° 


79° 


" 24.... 


86° 


87° 


85° 


" 25.... 


78° 


84° 


80° 


" 25 


79° 


82° 


82° 


" 26.... 


77° 


82° 


76° 


" 26.... 


80° 


86° 


84° 


" 27.... 


74° 


82° 


77° 


" 27. . . . 


81° 


86° 


83° 


" 28.... 


74° 


78° 


79° 


April 3.!!! 


82° 


84° 


84° 


Mar. 1.... 


75° 


80° 


78° 


" 4.... 


80° 


83° 


82° 


" 2.... 


73° 


80° 


78° 


" 5.... 


80° ■ 


81° 


83° 


" 3.... 


74° 


80° 


76° 


" 6.... 


81° 


84° 


87° 


" 4.... 


75° 


77° 


77° 


" 7.... 


84° 


84° 


81° 


" 5.... 


74° 


80° 


76° 


" 8.... 


82° 


82° 


86° 


" 6 ... 


74° 


79° 


76° 


" 9.... 


83° 


84° 


88° 


" 7.... 


74° 


79° 


79° 


" 10.... 


84° 


84° 


80° 


" 8.... 


73° 


78° 


77° 


" 11.... 


82° 


84° 


82° 


" 9.... 


74° 


78° 


76° 


" 12.... 


82° 


85° 


84° 


" 10.... 


75° 


80° 


77° 


" 13.... 


80° 


84° 


84° 


" 11.... 


76° 


81° 


81° 


" 14.... 


80° 


86° 


78° 


" 12.... 


76° 


81° 


80° 


" 15.... 


80° 


86° 


78° 


" 13.... 


78° 


84° 


81° 











It will be remarked that in the foregoing table the temperatm^es are 
given for midnight, noon, and 8 p.m. But as the soundings were 
usually taken at other hours, more commonly at 3 p.m., I give in the 
following table the temperatures observed at those hours, both at the 
surface and at the depths specified. 



20 



Table YI. 

Temperature of the Air, of the Sea-surface, and of the water at various deptlis. 





Date. 


Hour. 


Latitude 


Lon^- 
tude. 


Temperature op 




Air. 


Water 
Sur- 
face. 


Water at various 
Depths. 


Feb. 

u 


23 

25 


2 P.M. 

3 P.M. 
3 P.M. 
3 P.M. 
3 P.M. 


8° 50' 
9° 15' 
10° 05' 
10° 42' 
11° 24' 
11° 26' 
11° 39' 
11° 35' 
11° 06' 
11° 32' 
12° 38' 
13° 03' 
13° 06' 
13° 08' 
12° 55' 
17° 13' 
17° 13' 
17° 08' 
17° 09' 
17° 09' 
17° 27' 
17° 27' 
18° 11' 
19° 12, 
20° 48' 
23° 19' 
23° 19' 


15° 47' 

17° 12' 
17° 35' 
17° 46' 
18° 09' 
18° 20' 
18° 33' 
19° 33' 
21° 55' 
29° 13' 
42° 31' 
44° 51' 
50° 38' 
53° 48' 
56° 46' 
67° 29' 
67° 29' 
68° 48' 
71° 47' 
71° 47' 
74° 33' 
74° 33' 
76° 

77° 54' 
83° 01' 
84° 17' 
84° 17' 


79° 

78° 
76° 
78° 
77° 
80° 
82° 
77° 
76° 
76° 
83° 
84° 
80° 
80° 
81° 
80° 
80° 
84° 
82° 
82° 
82° 
82° 
85° 
84° 
84° 
84° 
84° 


78° 
79° 
74° 
77° 
76° 
77° 
77° 
76° 
77° 
75° 
76° 
76° 
75° 
79° 
80° 
84° 
84° 
84° 
84° 
84° 
84° 
84° 
85° 
85° 
85° 
86° 
86° 


200 fath. 
200 fath. 
200 fath. 
200 fath. 
200 fath. 
200 fath. 
200 fath. 
200 fath. 
200 fath. 

'266 'fath.' 
200 fath. 
200 fath. 
400 fath. 
100 fath. 
100 fath. 
400 fath. 
200 fath. 
200 fath. 
500 fath. 
300 fath. 
400 fath. 
200 fath. 
200 fath. 
200 fath. 
100 fath. 
200 fath. 


54° 

58° 


u 


26 


60° 


u 


27 , 

28 


60° 
53° 


March 


1 


53° 




2 




53° 


(( 


3 


3 P.M. 
3 P.M. 
3 P.M. 
2 P.M. 
2 P.M. 
11 A.M. 
2 P.M. 
2 P.M. 


53° 


K 


4 


52° 


U 


6 

10 


"56°* 


u 


11 


51° 


(( 
u 


13 

14 


51° 

47° 


u 


15 


62° 


April 


4 


70° 


4 


3 P.M. 
3 P.M. 


48° 


(( 


5 


59° 


u 


6 


62° 


u 


6 


4 P.M. 


48° 


u 


7 


54° 




7 

8 


4 P.M. 

3 P.M. 
4i P.M. 

4 P.M. 


50° 
62° 


(( 


9 


62° 


(( 


11 


62° 


u 


13 


72° 


(( 


13 


5 P.M. 


62° 









For a proper appreciation of the conclusions to be drawn from these 
tables, it is necessary to point out the facts indicated by the soundings 
of the ship. For the sake of brevity I restrict these remarks to the 
second stage of the voyage. 



Parting from the African coast, 
the bed of the ocean sinks very 
rapidly. A couple of degrees west 
of the longitude of Cape Yerde the 
soundings are 2,900 fathoms. From 
that point the mean depth across 
the ocean may be estimated at about 
2,400 fathoms, but from this there 
are two striking departures — first a 
depression, the depth of which is 
3,100 fathoms, and second an eleva- 
tion, at which the soundings are only 
1,900 — the general result of this 
being a wide and deep trough on 
the African side, and a narrower 
and shallower trough on the Amer- 
ican. It may be that this peculiar- 
ity is a result of the river distribu- 
tion on the two continents respect- 
ively, there being, with the excep- 
tion of the Senegal and Gambia, no 
important streams on the African 
side, whilst on the American there 
are many, and among them, preem- 
inently, the Orinoco and the Ama- 
zon, these vast rivers carrying their 
detritus far out to sea, and helping 
to produce the configuration of the 
ocean-bottom in question. How- 
ever this may be, it is doubtless 
through these deep troughs that 
much of the cold water of the ]S"orth 
Polar current finds its way. 

In accordance with this, we per- 
ceive, on examining the tempera- 
ture of the water, after the African 
verge of the greater or eastern sea 
trough is reached, that there is a 
difference in temperature between 
the surface and that at a depth of 




22 











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23 

not more than two liundrecl fathoms, exceednig twenty-five degrees 
in many cases. This decline of temperature inci'eases as the depth 
increases, one observation giving an additional fall of four de- 
grees at an additional depth of 200 fathoms. It is not, however, in- 
tended to affirm that the mass of cold water is restricted to these deep 
troughs, since even in the West India seas, at similar depths, low tem- 
peratures are observed, and this, though the heat of the surface-water 
has become very much higher. In those seas, while the surface tempe- 
rature was 84°, the thermometer, at depths of 400 and 500 fathoms, 
marked 48°, and these, it must be remembered, were the indications of 
an uncompensated insfruraeut, which was bearing a pressure of at least 
half a ton on each square inch of its surface, and hence registering 
deo^rees that were hi^'her than the truth. This accords with the ob- 
servation of Mr. Barrett, that in the deepest part of the sea, near 
Jamaica, there exists a temperature not far above that of the freezing 
point of fresh water. 

The foregoing diagram represents the temperatures of the air, those 
of the surface of the water and at different depths, usually, however, at 
200 fathoms, from Sierra Leone to Barbadoes, and from Barbadoes to 
Havana. The solid line represents the temperatures of the air, the 
dotted line that of the surface of the water, the broken line that of the 
water at 200 fathoms Here and there, as will be easily recognized, 
isolated observations at 100, 300, 400, and 500 fathoms have been in- 
troduced. The vertical lines indicate longitudes, the degrees of tem- 
perature are seen at the side. 

This diagram shows that the air line, after its oscillations near the 
African coast are over, exhibits a general rise to Barbadoes and thence 
to Havana. There is, however, a marked departure from the gradual 
character of this rise at a distance of about two-thirds of the way 
across. The surface temperatures are for the most part lower than the 
air temperatures, until the West India seas are reached, when they 
become higher. They do not exhibit that sudden rise observed in the 
air temperatures at 45° west longitude. The line of deep-water tem- 
peratures is, of course, lower than that of the surface all the way across, 
and exhibits the same contour in a general manner as the surface-line, 
rising as it comes into the Caribbean Sea. 



24 

From Table TV. it appears that the specific gravit}- of the water be- 
comes greater as the location is further west. This conclusion I found 
to be confirmed by an examination of the solid residue left after evap- 
oration to dryness of different samples. I need not quote many of 
these confirmatory experiments. It will be understood that the cus- 
tomary care was taken in ascertaining the weight of these solid residues 
to avoid hygrometric complication and the escape of their more volatile 
ingredients. As an example, it may be mentioned that surface water 
taken near the African coast on March 1, gave 39.600 grammes of 
solid residue in 1,000 grammes of water, and another sample of 
surface-water taken on April 10, in the Caribbean Sea, gave 40.520 
grammes in 1,000 grammes. It is probable that the concentration 
here remarked was due to the drying effect of the north-east trade 
wind. 

The specific gravity of the surface-water is of course affected by the 
rate at which evaporation is taking place, a concentration ensuing as 
evaporation goes on, and the density becoming greater. There is, 
therefore, a tendency in such concentrated waters to leave the surface 
and pass downward, until they reach a region in wdiich the density cor- 
responds to their own. These considerations have led some persons to 
suppose that this descent w^ould be continued to very great depths, and 
that this movement must sensibly affect the general motion taking place 
in the w^aters of the sea. If, however, we compare the density of the 
surface-waters in the tropical Atlantic as I have represented them in 
the foregoing tables, with the density of surface-water in higher lati- 
tudes, where both the air and water are much colder, and wdiere evapo- 
ration is much less active, as shown, for instance, in latitudes between 
50° and 60° north in the cruises of Dr. Carpenter, we see how small 
the difference is. When w^e remember, also, how slight a variation of 
temperature, as has been already said, completely masks these differen- 
ces arising from concenti-ation, we may safely conclude that the cause 
of disturbance may be overlooked. 



25 



In the adjoining diagram the ver- 
tical lines represent longitudes, the 
horizontal lines speciiic gravities, the 
solid line specific gravities of the 
surf ace- water, the dotted specific 
gravity of water at two hundred 
fathoms. On comparing the two 
latter lines together, we see that they 
almost coincide ; and again, on com- 
paring this diagram with that of 
the temperatures and also with the 
cross section of the Atlantic basin, 
a curious resemblance will be readily 
detected, viz., that they all exhibit 
an elevation about the meridian of 
45° west longitude, as though the 
contour of the bottom was not with- 
out influence on the physical state 
of the water above it. 

The general conclusion which 
may be drawn from these results as 
to temperatures and specific gravities 
is, that there exists all over the bot- 
om of the tropical Atlantic and Car- 
ibbean Sea a stratum of cold water, 
— cold, since its temperature is be- 
low 50°. This is the conclusion to 
which Dr. Carpenter has come, as 
respects the Atlantic in higher north 
latitudes ; and in this important par- 
ticular the cruise of the Mercury 
must be considered as offering con- 
firmatory proofs of the correctness 
of the deductions drawn from the 
cruises of the Lightning and Por- 
cupine. 

There are reasons for supposing 
that, so far from this water being 



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•AiiAvya 3Ui03ds 



26 

stagnant, its whole mass lias a motion toward tlie Equator, wliilst the 
surface-waters in their turn have a general movement in the opposite 
direction. 

As the samples of water had already been kept for some months 
before they came into my possession, though the}^ had been confined, as 
has been said, in bottles closed by corks covered w^ith sealing-wax, 
their gaseous ingredients must have undergone much change, I have 
already pointed out the disturbance that necessarily ensues in these 
gaseous ingredients as they are being draw^n to the surface, and another 
disturbance occurs when they are brought more fully in contact with 
the air on being poured into the bottles. Interchange by diffusion then 
rapidly takes place, tending to make their proportions approach those 
of surface-water. For these reasons I did not consider it necessary to 
make an analj^sis of the gases afforded by these specimens. Dr. Car- 
penter, from his experiments, concluded that when freshly-drawn water 
is tested, the proportion of carbonic acid increases as the stratum of 
water is from deeper sources. 

I made some examinations of the organic matter contained in these 
waters, both by incinerating the solid residue and by the permanganate 
test. It has been customary to divide such organic ingredients into two 
groups, the decomposed and decomposable, in investigations respecting 
the sustenance of animal life at great ocean depths. To estimate the 
relative proportion of these groups, a sample of the water is divided 
into two parts — one is acidified, and then to both an excess of a standard 
solution of permanganate of potassa is added. After three hours, 
iodide of potassium and starch are introduced to check further reac- 
tion, and the excess of permanganate in each sample is then estimated 
by a standard solution of hyposulphite of soda. From the portion to 
which free acid was added the decomposed and easily-decomposable 
organic matter can be estimated, and from the other the decomposed 
alone. I resorted to this method of examination in several instances, 
but was discouraged from prosecuting it, for such reasons as have 
already been stated in the foregoing case of the gaseous constituents. 
It needed no special j)roof that organic matter was present in every one 
of these samples, for the clearest of them contained shreddy and floccu- 
lent material, some of them quantities of sea-weed in various stages of 



decomposition. With these vegetable substances were the remains of 
minute marine animals. As bearing upon this subject, I found, on 
incinerating the solid residue of a sample of water taken from two hun- 
dred fathoms, that the organic and volatile material was not less than 
eleven per cent, of the whole. Though the quantity of organic substance 
diminished as the stratum under examination was deeper, there still re- 
mained a visible amount in the water of four hundred or five hundred 
fathoms. It is probable, therefore, that even at the bottom of the ocean 
such organic substance may exist, not only in solution affording nutri- 
ment to animals inhabiting those dark abysses, as Professor Wyville 
Thompson has suggested, but also in the solid state. Plants of course 
cannot grow there, on account of the absence of light. 

In order to determine whether any hitherto-unknown element existed 
in these w^aters, I subjected the solid residue to examination with the 
spectroscope, volatilizing the substances by the aid of a voltaic current 
and induction coil. A careful examination did not reveal the presence 
of any spectral lines, other than those belonging to the well-knowu 
elementary substances in sea-water. 

The specimens of the bottom, obtained by attaching to the sounding- 
line quills or wooden tubes, I have transmitted to Dr. Carpenter, who 
has kindly consented to 'examine them. 

In a letter dated August 10, 1871, recently received, he says : "As far 
as I can see, they consistof the ordinary Atlantic mud, chalk in process 
of formation, with the ordinary types of deep-sea foraminifera." The 
chemical composition of this mud, according to Mr. Forbes, as taken 
from soundings at 1,443 fathoms in the North Atlantic, is : 

Carbonate of lime 50.12 

Alumina (soluble in acids) 1.33 

Sesquioxide of iron (soluble in acids) 2.17 

Silica (in a soluble condition) 5.04 

Fine insoluble gritty sand (rock debris) 26.77 

Water ' . 2.90 

Organic matter 4. 19 

Chloride of sodium and other soluble salts 7.48 

100.00 
All of which is respectfully submitted. »=___ 

HENRY DRAPER, M.D. 



28 

SCITOOL-SHIP MeRCUEY, ) 

New York, April 29, 1871. j 
Sir — I would respectfully submit to your Honorable Board the fol- 
lowing report of all reliable deep-sea soundings made from this ship 
during her late practice cruise, together with a description of the man- 
ner in which they were made. The soundings were taken within the 
parallels of eleven and thirteen north latitude, from the coast of 
Africa, in the vicinity of Sierra Leone, to the Island of Barbadoes, 
W. I., through the Caribbean Sea to the west end of Cuba. The 
instrument used was a detaching apparatus, invented by the late Lieur 
tenant J. M. Brooke, U. S. ]^., and supplied to this ship through the 
kindness of Commodore James Alden, Chief of the Bureau of Navi- 
gation, Navy Department, AVashington. I found it worked admirably, 
never failing to bring up specimens of the bottom, except when coming 
in contact with rocky bottom. The quills inserted in the cell or holder, 
as seen in the accompanying sketch of the apparatus, preserve tha 
specimens in better condition for microscopic examination than the 
ordinary " arming" of soap or tall(~>w would bring up. 

Two spherical shot, weighing thirty-two pounds each, were used at 
every cast as a sinker, the sounding-line made of cotton, one-seventh of 
an inch in diameter, capable of sustaining one hundred and sixty 
poimds in the air ; the cord carefully waxed to overcome, as much as 
possible, the resistance of the line from friction of the water. x\ll 
soundings were made from a boat, as repeated trials satisfied me that 
no reliance could be placed on those made from the ship, on account of 
the difficulty of keeping the vessel in position and the line " up and 
down." A boat, fitted expressly for the purpose, with a reel holding 
four thousand fathoms, working on friction rollers, the line passing 
over the bow through a leader, thus enabling the boat, with the aid of 
oars, to be kept in position and the line perpendicular on the shot, thus 
determining to a certainty when the sinker reached the bottom. 

Temperature and specimens of sea-water at various depths were 
obtained by a self -registering metallic thermometer carefully adjusted ; 
all specimens secured have been carefully preserved, and now await 
your order. All soundings were made under my immediate super- 
vision, and the position of the ship at the time of sounding carefully 
noted, for which I respectfully refer you to the accompanying table. 
Yery respectfully, your obedient servant, 

P. GIRAUD, Captain. 
Isaac Bell, Esq., President, etc. 



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From Hart's Island, 

Rough sea, ship rolling heavily. 

Rough sea, ship rolling heavily. 

Fresh gale, high sea. 

Heavy gale, accompanied by fnrious 

squalls. 
Light breeze, confused sea, sky overcast. 
M(jderate breeze and pleasant weather 

throughout. 
Current ENE twelve miles, sky overcast. 
Moderate breeze and pleasant. 
Moderate breeze and pleasant, passing 

clouds. 
Moderate breeze and fine weather. 
Fine weather, light passing clouds. 
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Moderate breeze and cloudy, sea rough. 
Moderate breeze and fine weather. 
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Fine weather. 
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Fresh breeze, passing clouds, rough sea, 

SSE current one knot per hour. 
Heavy passing squalls, squally, rolUng 

swell NW. 
First part fine weather, second part 

squally and rainy. 
At 9 A.M. anchored at Funchal, Madeira, 

lat. 32° 38', long. 16° 55'. 


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